US2522055A - Electronic translating device - Google Patents

Description

Sgpt. 12, 1950 J. c. O'BRIEN 2, ,0

ELECTRONIC TRANSLATING DEVICE Filed Dec. 31, 1945 's Shegts-Sheet 1 Frequency Multiplier Harmonic Generator J H15 ATTORNEY Sept. 12, 1950 J. c, 'BREN 2,522,055

ELECTRONIC TRANSLATING DEVICE Filed Dec. 51-, 1945 v s sh eetse-sheet. 2

Fl G020 $35 BN2 41 Freuency AC Multipl r Harmonia Genera-tor qm w A Multiplier or Harmonic Generator H15 ATTORNEY Frequency AC 64 Multiplier E Harmonic 5 v Generator I J. C. OBRIEN ELECTRONIC TRANSLATING DEVICE Sept. 12, 1950 3 Sheets-Sheet 5 Filed Dec. 31, 1945 2 OIIIYVENTQRQ I WM. m

ms ATTORNEY Patented Sept. 12 1950 ELECTRONIC 'rasivsts rnve nsv os John O. O'Brien, Rochester; N. Y., assignor to General Railway. Signal Company, Rochester,

Application December 31, 1945, Serial No. 638,546

Claims. (01; sis-21) This invention relates to an electron tube of the rotating electron beam type and more particularly to means for variably rotating and variably focusing its beam during such rotation so that the beam will move quickly from anode to anode and will hesitate while on such anode orplate.

Rotating electron beam type tubes, such as disclosed in the Skellet Patent No. 2,217,774 may be used to perform various kinds of communicating and commutating functionsat high speed. Since no useful function can be performed and no electrons should flow from cathode to anode while the electron beam. moves from one anode to another anodeit is desirable to perform the beam shifting function between plates very.

quickly.

In accordance with the presentinvention it is proposed to provide electromagnetic means for concentrating the electrons emitted, by the cathode of the tube into a comparatively narrow beam,

and to cause rotation of such electron beam by causing rotation of the magneticfield which'concentrates the electrons into the narrow beam. Since rotating electron beam tubes of the type under consideration preferably employ more than two anodes it is difiicultto get slow movement of the rotating magnetic field while the electron beam is on an anode and fast rotation of such electron beam while it is shifting from one anode to another by the wave form of the fundamental wave of the alternating current, and'it has been found necessary to superimpose upon thefundamental frequency usecl'for rotating the electron beam a higher frequency wave, the frequency of which higher frequency wave has some relationship to fundamental frequency and to the number of anodes equally spaced about the cathode of the tube, and in accordance with the present invention it is proposed to combine alternating currents of two frequencies or combine alternating current magnetic fields of two frequencies in a manner to produce step-by-step rotation of the magnetic field and the electron beam rotated thereby.

In accordance with one form invention it is proposed'to use a laminated iron stator and to wind two difierent windings thereon and energize these windings with alternating currents, one of which has a frequency which is a multiple of the frequency of the other.

In accordance with another form of the present invention it is proposed to use. alternatin current voltages of different :frequenciesin series or in multiple with each other and apply them to the same winding taproduce a stemby-step of the present;

rotating magnetic field,

this being accomplished either by employing the two alternating current voltages in series, by employing the two alternating current voltages in multiple before. phase splitting of such voltages has been accomplished, or by connecting these voltages in series or-mu'ltiple after such phase splitting has been accomplished to produce a rotating magnetic field oi the step-by-step type. 1 {It has been observed that the ratio of the fre quencies of the two alternating currents employed isnot directly proportional to the number of anodes employed in'the tube but is proportional to either the sum of the anodes plus one" or the sum of the anodes minus one, de-

pending upon whether the supplementalor high frequencymagnetic fleld'is rotated in the same or the reverse direction as the fundamental frequency field is rotated.

Another feature of the present invention resides in the provision of a suppressing screen which hasappli'ed thereto alternating current potentialsjtofsuppress one end of the double electron beam that'is inherently produced by th V rotatingmagnetic field above mentioned.

'Other objects, purposes and characteristicfeatures of the present invention will in p'artbe pointed out in the specification hereinafter and will in part be obvious from. the accompanying drawings in which: W

s Fig. 1 illustrates an arrangement wherein'magnetic fields of different frequencies are combined to produce a step-by-step rotating magnetic field;

Fig. 2 illustrates a, modified form of the p ies- ;ent invention in which two alternating currents ofdifierent frequencies are applied to the same phase splitting network which is in turn connected to a single polyphase winding to produce a step-,by-step rotating magnetic field;

Fig. 3 illustrates a modification of the form of invention illustrated in Fig. 2 in that the stator structure is somewhat diiierent and in that the two alternating current voltages of diiferentfre- .quenoies' are included in series whereas in Fig. 2 they are included in multiple;

Fig. 4 illustratesa modified form of the invention illustrated in Figs. -1 and 2 and in this case each of the two alternating currentfrequencies has itsown phase splitting network as inFig. .1 and: these networks are then connected in multiple to polyphase windings such as illustrated in Fig. 2.

Fig.1 fi'illustrates vectorially and graphically the manner in whichthe electromagnetic field --the 'same extent.

' 3 rotates when the higher frequency is equal to the lower frequency multiplied by the number of anodes plus one and when both vectors rotate in a clock-wise direction as is the case in the specific circuit arrangement shown in Figs. 1 and 4; and

Fig. 6 illustrates vectorially and graphically the manner. in which the rotatingmagnetic field performs it's"rotating: and hesitating function when the higher frequency is equal to the lower frequency multiplied by the number of anodes minus one and when these vectors rotate in different directions as is true of the forms 'ofinvention illustrated in Figs. 2 and 3 where the two rotating vectors rotate in opposite directions.

StructureFig. 1.--Referring to Fig. 1 the roth e two alternating-===- V forces' and the resultin riagiietic fields rotate in two magnetic fields thus rotate in opposite directions. Since however the field produced by winding H is dominant the net rotation of the field is in a clockwise direction.

Since the particular embodiment of the invention shown in Fig. 1 employs an electron tube having four equally spaced anodes P and since urrent magnetomotive opposite directions it is essential that the high frequency current produced by the frequency tating beam electron tube of the present invention comprises a cylindrical envelope or tube [0 preferably constructed of glass which :is highlyevacuated and contains a cathode Ca, a plurality :of anodes P each anode of which is provided with asuppression grid Gs and each tube is' preferably provided with a single control grid Gc although a separate control grid for each anode maybe employed if desired. This-tube I0 is surrounded by an iron stator ISI preferably built up from laminations of extremely small thick- .nesses of low hysteretic loss material so as to reduce the eddy current losses and allow high frequency magnetomotive forces to be set up therein. This stator ISI is preferably circular with suitable windings thereon and is of a size to just barely receive the electron tube l0 and this stator 'is so constructed that internal rather than external magnetic poles are produced therein. As shown in Fig. 1 this stator ISI comprises a stator of the Gramme type on which two separate and continuous windings are placed. The winding H has been shown by heavy lines and the winding l2 has been shown 'by light lines although in practice the wire sizes may be "substantially the same. As illustrated the heavy winding l l is energized from an alternating current generator AC through the medium of a phase shifting network including condensers Cl and C2 and resistance units RI and R2. The "condenser Cl and the resistance unit RI have such electrical values that the potentialapplied to the point 55 lags the potential applied to the point 14 by substantially 90 electrical degrees and the condenser 02 and resistance unit R2 have electrical constants such as to cause the potential at the point I! to lag the potential at the point 56 in phase relationship to an extent of substantially 90.

Inorder to cause the rotating magnetic field of the higher frequency supplied by the frequency multiplier FM! to rotate in the opposite direction the phase shifting network 03, R3, C4, R4 have been inversely arranged as illustrated in Fig. 1. As a result of this reversal of elements the potential applied to the point 25 of the winding [2 lags the voltage applied to the point 26 on this winding to an extent of substantially 90 electrical degrees and likewise the voltage applied at the point 27 of this winding 12 lags the voltage applied to the point 24 to substantially The voltages applied to the points [6 and 26 of the windings H and-l2 are "respectively of inverse potential to. that 'of the points l4 and 24 respectively. In other words, the'rotating magnetic field producedby winding ll rotates in a clockwise direction whereas the frotating magnetic field producedbywinding l2 -rotates in-a counter-clockwise direction. The

.multiplier PM! he of a frequency which is three "times that of the frequency of the alternating current. plOdllCEdbY the generator AC and it is :proposed'thatthe frequency multiplier FMI be constructed t perform a frequency tripling function. Thefundamental frequency current may be of any desired frequency within limits permitted by eddy current and hysteretic losses.

Operation--Fig. 1.-%Referring to Fig. 6 of the drawings; let us assume :thatthe magnetomotive force vectori28 is the.magnetomotiveyforce produced by the-voltage producedbythe generator AC (Fig. '1) and thatthe-magnetomotiveforce vector 29 is produced-:by current derived from the frequency multiplieriFMl 'andthat at during the particular instant under-consideration these .two voltagesare-in phase 'as illustrated in Fig; 6. .Let us now assumerthat the low: frequency voltage'vectorshifts to theflpositionml to: trace the right another 30 from the position Silto the position 32, the high speed'voltage' vector "shifts counter-clockwise another as .illustratewby the magneto-motive forceyector line 33 11h "other' rdSQdu'ring this'30" smaof the fundamental magnetomotive force vector the combined result ofthe'two'magnetomotive force vectors has shifted the entire magnetic 'field to'an extentiof substantially or slightly in'excess of 9'0" while the fundamental magneto-motive force only shifted to an"exteht oflso". Inlo'therword sltifie rotating magnetic field stood.substantially-still during a 60". shift o i .the fundam'ental=magnetomotive force and then madeza rushing sweepof substantially a 90.1shiftr duringa 30? lsh rtlor the fundamentalmagnetiofield. It is,-thus seen that the magnetic fleld rotates step-by step in ;ashigh as is.thedowersfrequency and-the results accomplished by the construction illustrated in Fig. .1 and graphically -analyzed .in Fig. 6 lends itself admirably :rtO .the employment ;of four zanodes in an electron ztube surrounded by :the

rotating magnetic .field gproducingl means: shown Another lthing that Jcan'be readily. seen-l from the curve 23 0f Fig. 6 ;is :that .the'magnetic field is strongest: during i-rthose times when it hesitates on:a plate or anode'land-iszweakest duringithose times of quick sweep from one anode to another. This is -3true because Fthe s'um ofthe r magnetomotive forces are accumulative .when theyrare substantially in phase, and aresubtractive when they are substantially out of phase. it being of course understood that the fast rotation of-the magnetic field takes place when these magnetomotive forces are substantially out of phase. In practicing the invention it may be desirable to have the strongest magnetic fields while the electron beam is being swept from one anode to another. This is true because when the magnetic field is strong a narrow electron beam exists and it is desirable to have a narrower electron while it is swept from anode to anode whereas a wider electron beam may be tolerated while the electron beam hesitates or stands still on a particular anode during its rotation. In view of these considerations it may be desirable to have a strong magnetic field while the electron beam is being swept from anode to anode and such a construction has been illustrated in Figs. 2 and 3 and has been graphically illustrated by the curve 49 in Fig. 5.

The operation of the Fig. 1 structure merely involves an observation of how the application of alternating current of fundamental frequency derived from the generator AC and applied to winding II in combination with a triple frequency produced by the frequency multiplier FM! and applied to the winding I? .may cause step-by-step rotation of the electron beam 20 in the tube or envelope Hi. This is especially true in that it is to be understood that a rotating beam electron tube may be used in many situations where fast commutation or circuit switching is to be accomplished. As illustrated, this electron beam 20 is not a double beam such as would ordinarily be produced by a, magnetic field of the type just described concentrating the electron emission from the cathode into a narrow path, that is, a two pole magnetic field. It should however be understood that the invention may be applied in the same way to a tube having a double electron beam. In order to suppress one of the two electron beams that would be inherently produced by a two poled magnetic field of the type under consideration, the electron tube I illustrated in Fig. 1 is provided with suppression grids Gs, one for each anode or plate P. These suppression grids Gs are, as shown, energized electro-statically directly from the fundamental alternating current frequency supplied by the generator AC and these potentials are such that their application to one suppression grid Gs aids the flow of electrons to the associated anode whereas the oppositely located suppression grid Gs being exposed to the other end of the electron beam opposes and suppresses the flow of electrons. From this it is readily seen that as the electron beam 20 rotates, the electrostatic potentials applied to the grids Gs also rotate and always suppress one end,.namely the end not shown, of the two beams whereas they aid electron flow for the other end, namely. the beam 20, of the two beams that would ordinarily result. It should be understood that the stator ISI is rotatably positioned on the electron tube l0 so that the relative position of the rotating magnetic field may be shifted with respect to the relative position of the anodes and screen grids as to produce the proper phase of relationship between these elements, the stator ISI of course being locked in position after it has once been moved to the proper phase shifted position. As shown, the stator ISI (Fig. 1) is shownshifted clockwise substantially 45 with respectitoe'zthe the potential producing the-particular magnetic pole. This has been-thus illustrated because the magnetism actually. lags-the. potential producing it and in practice this lag. may be more nearly degrees so that additional shifting ofthe stator ISI in a clockwise direction may be necessary.

Since the various voltages applied to the various screen grids Gs should have potentials with respect to ground, .a grounding network including resistances I 8, l9, 2land 22 has been-provided for the main winding H whereas similar grounding resistances 35, 36, 31 and 3B havebeen provided for the supplemental winding l2. It will be observed that these resistances i8, l9,-2-I and 22 and 35-38 are connected in star fashion with the star point connected to. ground as conventionallyv shown- By the employment of. these-resistances, a definite voltage gradient exists. between the cathode Ca which is also grounded and the various screen grids Gs. Structures-Fig. 2.In Fig. 2 ha'sbeen illustrated an electron tube [0 of identical construction as that shown in Fig. 1. This tube is surrounded by a, Gramme type core structure 182 provided with a single winding 40 instead of the two windings shown in Fig. 1. In this casea single phase shifting network comprising the condensers C5 and C6 and the resistance-units R5 and. R6 is employed and this phase. shifting network is fed by the fundamental frequency alternating current-derived from the generator AC and in multiple therewith is also fed by alternating current derived from the frequency multiplier FMZ. Since in this construction, only one phase shifting network is employed; the low frequency alternating current and the high frequency alternating current applied to the winding 40 will of necessity rotate in the same, namely, the clockwise, direction and for this reason and reasons already pointed out hereinbefore, the supplemental frequency derivedfrom the frequency multiplier FM2 must be equal to the fundamental frequency multiplied by the number of anodes plus one. That is, must be five times that of the fundamental'frequency since a four anode electron tube III has been illustrated in Fig. 2. The phase splitting network; C5, R5, C6, R6 is designed to obtain the desired phase shift for the fundamental frequency current and thus will produce slightly more but less than 90 phase shift for the supplemented and higher frequency current. It will therefore serve-admirably for currents of both frequencies. It will be observed that a tuned unit ll-42, comprising a condenser 4| and an inductance 42 in multiple, is used to pass the low frequency current and block the flow of high frequency current, and

that a similar tuning unit 43-44,- comprising a condenser 43 and an inductance. is employed to pass the high frequency current andblock the flow-of low frequency current. These tuning units 4l42 and 43-44. are resorted .to to allow the flow of current only into the circuits for which they are intended and to prevent one source of current from becominga loader short circuit for the other source of curent.

In oder to properly ground the cathode Ca (Fig. 2) with respect to the midpoint of all of the potentials applied to the winding-.40 and the screen grids connected thereto, the.' groundnetwork, including resistance units 85, 46,. 41, and 48, has beenprovided'in-Fig; 2. The purpose of this group of resistances 'connectedis'in star rfas'hionihas alreadyibeen explainedin connection vwithzFi ximfi-the drawings.

t0.per.ation.-?Eig.t?2-.-As already pointed out'the fundamental or *low frequency-current and the ts'upp'lemental tor high f frequency current applied "to the structure of Fig. 2'produees rotating mag- -netic fields :which :rotate 'inzthe same -directi0n because the same phase splitting net-work ismsed for both alternating currents and also for rea- "sonsheretofore' pointed out, the frequency of the supplemental alternating current is five times that of the fundamental alternating current frequency. Referring now:to'Fig. :5 ofthe-drawings, let .us assume that the voltage vector is the voltage derived from :the generator AC (Fig. 2)

'and'that the voltagevector. 5 is derived from the .tfrequency multiplier FM2 and that these two voltages are in phase as illustrated in Fig. 5. Since the fundamental frequency is only onefifth that of 'theauxiliary frequency let us as- .sume :that an instant of time later when the fundamental frequency has shifted 18 (onefifth of 190) as illustrated by the-vector 52, at which itime'the high frequency-vector has shifted to anextent of 90 as illustrated at 53. It is thus seenthat the magnetic phase rotation produced by the stator 1S2 and-its winding 45] has shifted from a position midway between two anodes to ,a.;position substantially directly over one anode during .an:.18 shiftof the fundamental magnetoimotive force and .that-the sum of the magneto- -m0tive forces was greatest when the speed of magnetic field was greatest, as shown by curve 49 (Fig. 5) .Let us further observe that during the next 18 of rotation of'fundamental mag- IIE'EOIIIOHVB force to the position indicated by the vector $.54, the auxiliary frequency again rotates --through an angleof 90 so thatpractically nonet rotationrof magnetic field hasrtaken place inthat the high speed vector when added to the :fundamental vector 54 results in practically no -net-phase. :shift. Letvus'now observe that during the;neXt 18 of. rotation of the fundamental mag- :netomotive force vector as. illustrated by the vecrtor 56 the high speed vector 51 actually rotates backwards to a. greater extent so that the magrneticufield does not only not advance but actually :rotates in thereverse directioneduring this onetwentieth of a revolution (18") of the magnetic field. By studying the graphic analysis illustrated bythe curve 49 in'Fig. 5 of the drawings it is readily seen the anodes should be placed at 'points45" displaced from :the-vertical and horizontal lines of the diagram as is also. true of the Fig. 6 structure.

theFig. 5 diagram the magnetomotive forces are strongest when the field shifts forwardly at a high speedwhereas in the Fig. 6 structure 'the magnetomotive forces are the smallest during :such fast-shifting of the magnetic ffield. Conversely the rotating beam isless sharply focused when the electron beam is aimed at an anode in :the Fig. 5 structure .whereas it is most sharply focused When in communication with an node in the structures the analysis Of'WhiG'h are shown in Fig. 6.

Structure and Operation-Rig. 3.--The embodiment ofithe invention illustrated in Fig. 3 .is identical to .that illustrated in :Fig. 2 except :that the iron stator I83 illustratedinFig. 3 is .a stator employing a magnetic structure having astmany salient .polesL59 as there are anodes, :there :being a single coil windin A60 .for each zsalientcpole .59, .and that .the 'voltages derived from :thersourcea-AC. and are connected It is also readily seen that in series in Fig. -as=distinguished=from dieing-connected in multiple as they -are=in' Fig. In the Fig. *3 structure there are provided two -by-pas's tuning units 61- 62 and 63- 64. The tuningunit including the condenser -61 and the inductance 62 in multiple has electrical constants such that it permits the 'flow of "low frequency current derived from-the generator A'C but blocks=the now of high 1 frequency current-derived front-the frequency multiplier -FM3-and the tuningunit fi -64 comprising acondenser -63 and an induc- -tance B4 in multiple, has electrical -constants such as'to block the-flow-oflow frequency-current deri-ved 'from the generator AC and' to' bypass the high frequency current derived from the frequency multiplier -FM3. Since the operation of "the structures-illustratedin'Figs. 2-and 3 are identical no "specific operation or discussion "of --vector diagrams-or other graphicalanalysis necd be given except'to say that the analysis illustrated by'curvemof Fig; 5 isapplicable.

Structure and Operatiom- Fig. 4.The -ap- 'paratus illustrated in Fig. 4 is very-similar to that illustrated in 'Fig. 1, these-devices differing-particularly in "that only one winding i5 is-contained on the stator IS'4. This winding 65-is supplied by alternating current from --two independent phase shifting and grounding networks similar to those illustrated in Fig. 1, these networks being supplied by alternating currents of dif- 'ferent frequencies as already explained in-con- 'nection with Fig. *1 of-the drawings. "It should be observed that a tuning unit including-tho condenser H and inductance "72 has-been provided in *Fig. 4 to pass alternating current of low frequency derived from the alternating current source AC, and to block the flow of'highfrequency current derived from the frequency-multiplier FM4. 'The condenser 1! and inductance "12 of this unit ll- 12 of course haveelectrical constants so as to performboth a"tuning* funetion for the low-frequency current and a-blockingfunction for the high frequency: current. 'It should alsobe noted that COIldGl'lSGI'SflB and "have been provided to ltune the transformers T11 and T12 respectively so that= the i -two-alternating current sources are-properlyisolated from each other by a :suitable 'tunedunit. That is, the-secondary windings of i'transformers 'Ih l and Tr? are tuned to passihigh frequency current-arid block the flow oflow frequency current. In-all other respects the structure of Fig. A i is similar 'to that-of Fig. 1 and :since both of' these struc- "tures produce 'the same operating results it is unnecessary :to specifically discuss-the operation of the-apparatus illustrated in Fig. :4. It -may, however, be -pointed :out that the f unctional 'resultsaof the Fig. 4- structure are graphicallyillustrated by the curve n ina-Fig. 6 of the drawings, the frequency of the high frequency current being "three-atimes the :frequency of the ilow frequencycurrent.

It-should be understood-that independent gen- *erators connected to: thesamexshaft or interconnected by gear connections may be :used instead 'Of the generator- A0 andllits associated frequency multiplying unit '-FM4 illustrated. In :th-isconnection= it shoulds-bel borne. in mindrthat: thee-two alternating currents =must haveaaconstant and fixed frequency ratio. .It should however %be nnderstoodrthat any: desired voltagearrelaticnship :within limits:.mayibetemployed' but:theyoltageaof the higher frequency energy :per-unitnofxim- :pedanceshould always be'tlws than 1. the lvoltage :ofrthe low:- frequency energy.

I t is further desired to point out that the rotate'lectron-beam tube of the'present invention lends itself particularly well to systems where such tubes are -connected in-cascadeor in tandem as is the case for systemsdllustrated,inthe prior filed pending application of Field} and Wight, ser. No. 599,328,,fi1 3d, June re, 1945, which has resulted in Patent No 2,488,431 dated August 31, 1 948. In that patenttwo rotating beam electron tubes are so connected in cirou its and are so controlled that the electron beam in one tube makes a complete revolution while the electron beam in another tube sweeps from engagement with one anode to engagement with another anode. In such a system it therefore becomes important that as little time as possible be lost by the beam of the slow tube in moving from one anode to the next anode in that it should be in communication with any particular anode during substantially the entire rotation of the electron beam of the fast tube and should then shift very quickly to another anode. The importance of rotating electron beam tubes whose rotating beam rotates in step-by-step fashion with varying sharpness of focusing should now be apparent not only where individual tubes are used separately but also where such tubes are connected in tandem.

Briefly stated the rotating beam electron tube, if used in accordance with the present invention, may be used to transmit a plurality of telephone conversations simultaneously but on the time allotment basis or may be used in a Synchronous type control or indication system by controlling simultaneously or in sequential relationship a plurality of devices from a distant point either over line wires or through the medium of space radiation, and performs these functions more emciently and more accurately than do mechanical devices.

Having thus shown and described numerous ways and means for causing an electron beam in an electron tube to rotate in step-by-step fashion and how to more sharply focus this electron beam either as it is moved from anode to anode, or as it hesitates on an anode, it is desired to be understood that these various examples in which the present invention may be practiced have merely been resorted to for the purpose of explaining the nature of the invention and its underlying principles and that various other gara e structures may be employed to accomplish the same or similar results and it should be understood that various changes, modifications and additions may be made in practicing the invention without departing from the spirit or scope thereof except as demanded by the scope of the following claims.

What I claim as new is:

1. In an electronic translating device, the combination with a sealed envelope, a cathode near the axis of said envelope, a plurality of anodes surrounding said cathode, suppression grids between the cathode and the anodes, and an electromagnet having a multiple phase winding surrounding said anodes, of circuit means for energizing said winding simultaneously by multiple phase alternating currents of two different frequencies, one frequency being a multiple of the other, whereby the resultant magnetic field rotates in a step-by-step manner, and means for electrostatically energizing said suppression grids with respect to said cathode from both of said frequency currents, whereby the electrons emitted by saidicathodei are formed into a racist can;

rotatedfromanode to anode in accordanceewith] the rotation ofv said resultant magnetic ea-, ,2..I n an electronic translating ,device,-.the,com:. bination with a sealed envelope, a cathodenear, the axis of said. envelope, a plurality-of anodes, circumferentially disposed about said cathode suppression grids between the anodes and the; cathode, and a two-phase electrornagnet s rounding-saidanodes, of circuit means for energizing said electromagnet by two-phase energy from two diiferent frequency currents simultaneously, one frequency being a multiple of the other, whereby the resultant magnetic field rotates in a step-by-step manner, and means for electrostatically energizing each of said suppression grids with energy of varying potential with respect to said cathode in synchronism with said rotating field whereby the electrons emitted by said cathode are concentrated into a beam extending radially from said cathode and scanning the respective anodes step-by-step in synchronism with the rotation of said resultant mag netic field. v

3. A rotating beam tube organization comprising, a centrally located cathode in an evacuated envelope, a plurality of anodes circumferentially disposed about said cathode, a suppressor grid between each anode and the cathode, a source of two-phase alternating current at a particular frequency, a source of two-phase alternating current at a multiple frequency of said particular frequency, circuit means for applying each of said frequency currents to said suppressor grids electrostatically in a manner to render such grids alternately positive and negative with respect to said cathode, a two-phase electromagnet surrounding said anodes, circuit means governing the energization of said electromagnet from both of said sources of alternating current simultaneously,whereby the electrons emitted from the cathode are concentrated into beams by the respective rotating fields ofsaid electromagnet and a single radial beam of increased concentration is formed-each time that the two frequencies are in phase.

4. In a rotated beam tube organization of the character described, the combination with a sin-, gle cathode centrally located in an evacuated envelop'e and a plurality of anodes circumferentially located about said cathode, of a two-phase electromagnet surrounding said anodes, and circuit means governing the energization of said electromagnet wherein rotating fields of different frequencies are set up in said electromagnet by the energization of said electromagnet with two-phase alternating current of two different frequencies, one frequency being a multiple of the other, and the lower frequency current pro-- viding a relatively stronger field than the higher frequency current, whereby the electrons are concentrated into beams by the respective rotating magnetic fields, a more concentrated beam being provided by the field set up by the lower frequency current, and that beam being intermittently concentrated to a still greater extent when both frequency currents are substantially in phase.

5. A rotating beam tube organization comprising, a single cathode centrally located in an evacuated envelope, a plurality of anodes circumferentially located about said cathode, a two-phase electromagnet surrounding said anodes, circuit means governing the energization of saidv electromagnet wherein said electromagnet is enermamas 11 gized simultaneously by two- -phase elternati g currents of two difierent frequencies, one imquengybejing a multiple of the other, whereby the electrons emitted from the cathode are'coneentra-tefl into beams by the respective rotating fields of sa-id'el'ectromagnet in response to energization simultaneously by the two different frequency currents and a single beam of increasingc'oncentration formed each time that the two frequencies are in phase.

JOHN C. OBRIEN.

BEFERENEES CITED UNITED STATES PA'I'ENTS'

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